Dear Mr. Chatterjee,

I suspect of having a rather small grain size in these mylonites to deal with. So the hot issue seems to be placed within the grain size. While under normal conditions (sand-size grain size interval) the separation of biotite and quartz should cause any bother using either Na-polytungstate as heavy liquid or the Frantz isodynamic magnetic separator, the separation of minerals mentioned under points 2 and 3 seems to be very difficult. If hand-picking is no option and the particle size still allows for physical separation high-field strength magnetic separation might be feasible. Flotation depends upon the purity of the resultant concentrate. It seems to me crucial to know what the scope of the separation is and the grain size of the minerals involved. Are there any other minerals which might interfere in the suggested separation processes. Without a proper knowledge of that, it is difficult to recommend a tailor-mode solution.

Best regards

Harald G. Dill

For (1), try repeatedly spilling and shaking the separate on an inclined frosted glass plate.  The quartz should roll and the mica should shuffle downslope, slowly.  Item (2) is very difficult unless you hand pick. Ask if quartz matters to analysis.  I am not sure what you mean by (3).

Prof. Harald Gill, thanks for your suggestion. I would like to inform you that 1) individual grain-size (under microscope) for muscovite and quartz that have been targeted would be less than 100micron, 2) the purpose of the separation is Ar-Ar dating and stable oxygen and hydrogen isotopic analysis, 3) other minerals that are present with even finer sizes are graphite, chlorite, orthoclase, garnet, staurolite (traces).

Prof. John Garver, thanks a lot for your kind suggestion. Actually, ITEM 3 would be

smaller flakes biotite from a small book of muscovite. What do you mean by frosted glass plate?

Nirmalya! I suggest you crush your sample to the required grain size (

Dr. Lar, I'm sorry to say that the density of bromoform is 2.9 approx. so it will not possibly work unless muscovite has sp.gr around 3.

Hi Nirmalya! In response to your comment above, please note that minerals with densities lower than the bromoform will float, which makes it easier to separate from the bulk sample. So muscovite which has a density lower than that of bromoform will certainly  float.

Dr. Lar, quartz and muscovite are both lighter than bromoform which makes the separation impossible by this method.

Nirmalya! I know that quartz has a s.g. of 2.65 and muscovite of 2.76-2.88. If separating these two minerals using bromoform (depening on bromoform's density) wouldn't work, then your best bet is to use either a Shaking Table (that will again depend on the quantity of your sample) or recourse to using a Frantz magnetic separator at different voltages (the operator's guide could help you). Let me know any method that finally works for you.